A flat-plate-shaped device under test such as an integrated circuit or a display board undergoes an electrical test with use of an electrical connecting apparatus such as a probe card. In the electrical test, the device under test with its electrodes contacting the contactors of the electrical connecting apparatus and is powered in that state.
As one of the electrical connecting apparatuses of this kind, there is an art of using a flexible circuit board having a flexible sheet-like member such as an FPC provided with a flexible electrical insulating sheet and a plurality of wires formed on the sheet, and contactors soldered to the respective wires of this sheet-like member.
Referring to: Japanese Patent Appln Public Disclosure No 2002-311049, which is incorporated by reference, each contactor comprises a pedestal portion coupled with the wire at one end portion, an arm portion extending from the other end of the pedestal portion in the longitudinal direction of the wire, and a probe tip portion protruded from the tip end of the arm portion to a side opposite the pedestal portion. The arm portion and the probe tip portion act as a main body portion that is elastically deformed substantially at the arm portion when the tip end of the probe tip portion, that is, the probe tip, is thrust to an electrode of a device under test.
The circuit board using such contactors is attached to a support board such as a wiring board by an attachment apparatus so that the probe tip portions can be directed to the device under test, thus to be assembled into an electrical connecting apparatus.
The attachment apparatus comprises a first reinforcing plate (plate-shaped member) arranged on the upper surface of the wiring board, a ring-shaped second reinforcing plate (ring-shaped member) arranged in a downward step portion provided at the center of the wiring board so as to be located at the step portion, a plate spring screwed on the lower side of the second reinforcing plate, and a table (block) having at least an attachment surface on the lower side and screwed on the lower side of the plate spring in a state where the attachment surface is protruded downward of the support board.
The first reinforcing plate is attached to the wiring board by a plurality of attachment screws penetrating the first reinforcing plate and the wiring board in the up-down direction and screwed in the second reinforcing plate and attaches the second reinforcing plate to the wiring board.
The aforementioned circuit board is bonded to the attachment surface of the table at a contactor area at which the contactors are arranged and is attached to the lower surface of the wiring board by a ring-shaped pressing plate and a plurality of locking screws at an outermost circumferential portion of an outer area surrounding this contactor area.
The above electrical connecting apparatus undergoes positioning (that is, alignment) in which the probe tips of the contactors are positioned relative to the coordinates of a testing apparatus such as a prober in a state of being attached to the testing apparatus. Thereafter, the electrical connecting apparatus is powered at an appropriate contactor in a state where the probe tip is thrust against the electrode of the device under test. By doing so, an electrical test is conducted.
The above positioning is performed generally by measuring the position of the probe tip of the appropriate contactor relative to the coordinates of the testing apparatus and thereafter changing the coordinates on the software of the testing apparatus or correcting the attachment position of the electrical connecting apparatus to the testing apparatus so that the measured position may be at an intended position on the coordinates of the testing apparatus. Such positioning is performed every time the electrical connecting apparatus is replaced.
Generally, as for the above electrical connecting apparatus, a check as to whether or not the powering state is good is performed on the side of a manufacturer of the electrical connecting apparatus before the electrical connecting apparatus is delivered from the manufacturer to the user. This check is performed by powering all the probes simultaneously or sequentially, or per plural probes in a state where the probe tips of all the contactors are thrust against a pseudo test piece.
Accordingly, in the conventional electrical connecting apparatus, even if the probe tip portion is cleaned after the check, foreign matters such as scrapes generated at the time of the check inevitably remain at the probe tip. Consequently, at the time of positioning on the user side, the foreign matters remaining at the probe tip lowers the measurement accuracy of the probe tip position, and accurate positioning is difficult.
Also, the above probe tip position is generally determined by directing light beam such as laser beam toward the probe tip and measuring reflected light from the probe tip by a measuring instrument or by capturing the probe tip by a video camera and performing electrical image processing to the output signals from the video camera.
However, since light from the vicinity of the probe tip is also incident in the video camera, it is difficult to electrically distinguish between light signals from the probe tip and light signals from the vicinity of the probe tip. Thus, this also lowers the measurement accuracy of the probe tip position, and accurate positioning is difficult.